A conventional minimally invasive procedure requires the use of gas (such as carbon dioxide) insufflation to lift the tissue or body wall from internal organs, thereby separating the body wall from the internal organs to create an operative space to introduce various surgical instruments to conduct the procedure.
The following patents disclose various tools for medical or surgical applications: US20030065358A1, U.S. Pat. No. 6,120,437A1, U.S. Pat. No. 6,099,550A1, U.S. Pat. No. 5,865,802A1, U.S. Pat. No. 5,823,947A1, U.S. Pat. No. 5,797,939A1, U.S. Pat. No. 5,766,169A1, U.S. Pat. No. 5,456,684A1, U.S. Pat. No. 5,336,220A1, U.S. Pat. No. 5,186,714A1, EP0614646B1, WO0193742A2.
The following patents disclose examples of medical devices, including trocar and instrument assemblies: US200383628A1, US 20030060770A1, US 20030023257A1, US20030004529A1, US20030004528A1, U.S. Pat. No. 6,582,441B1, US20020198554A1, US20020183775A1, WO9410898A1, JP11089851A, JP07047076A, JP05228160A, JP04263849A, JP04253852A.
Though insufflation is commonly used, non-gas based methods have been proposed. For example, such methods may use mechanical devices wherein the tissue is lifted externally or by provided internal stirrup like supports of different mechanical assemblies to lift the tissue to create the operative space without the use of gas. One method employs a vacuum actuated tissue lifting device. The following US patents are incorporated herein by reference for disclosure related to lifting devices and methods, including vacuum lifting devices and methods: U.S. Pat. No. 6,042,539, U.S. Pat. No. 5,938,626, U.S. Pat. No. 5,893,368.
The method described in U.S. Pat. No. 6,042,539 describes a vacuum shell and provides a “dome” like operative field within the patient. An optical trocar having an obturator and cannula sleeve may be employed with such a vacuum shell. However, there can be difficulties related to use of such a trocar with vacuum assisted surgery and/or surgery without insufflation.
For instance, conventional trocars can have a working length that is not sufficient for such an application (working length can be defined as the actual length of the tubular section of a trocar below the sealing surface of the trocar). On the other hand, a trocar with an increased length may be difficult to maneuver and may restrict movement during the surgical procedure.
Additionally, it may not be desirable to use a conventional bladed trocar with a vacuum shell or other vacuum lift device, due to the possibility of accidental contact with internal organs during a first “blind” entry into the body cavity. Even if an optical obturator is employed, skill is still required to introduce and monitor the position of the trocar tip simultaneously. Also, introducing the camera assembly into the trocar obturator can result in a bulky (difficult to handle) assembly during the step of penetrating the body tissue.
Moreover, a conventional trocar which has a fixed length may not be suitable for all patients. Different patients can have different thicknesses of the abdominal wall and/or the fatty layers associated with the abdominal wall. For example, a thin or normal weight patient may require a trocar having a certain length, while a relatively obese patient may require a longer trocar.
Another problem with using a conventional trocar in vacuum assisted surgery is that when the trocar is inserted after the vacuum shell is placed on the tissue, the trocar will first cut through the perforable membrane of the shell, then pass into the patient's tissue. If the user attempts to penetrate the body wall without the application of vacuum to the vacuum shell, body wall will tend to buckle under the penetration force, and it is possible that internal organs could be injured. On the other hand, if the conventional trocar is inserted after applying vacuum and obtaining a partial or full lift of the abdominal wall from the internal organs, the internal body cavity and organs below the abdominal wall may also “lift”. Movement of the bowels under peristalsis can become sluggish due to the effects of anesthesia, which may lead to the formation of pockets of trapped gases. These trapped gases can expand under vacuum, and may result in reduced operative space and increased gas pressure in the lumens of the bowel. Also, in the case of abdominal surgery, the time during which the intra abdominal cavity is under vacuum can lead to pulling of the diaphragm into the abdominal cavity, and can create a negative pressure in the thoracic cavity.